Migate more of Pholio to Modular Transaction

Summary: Another Franken-transaction. Adds transactions for ImageName and MockName. Adds transaction-level validation for presence of mock name; removed same from edit controller. Removes PholioTransaction::getRemarkupBodyForFeed(), which appears to be dead code since that method isn't defined on any other types.

Test Plan: made a bunch of changes to pholio mocks and images and observed expected results

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: Korvin, chad, epriestley

Differential Revision: https://secure.phabricator.com/D17865